Nuclear Engineering Commons^™

Characterization Of Two Ods Alloys: 18cr Ods And 9cr Ods, Julianne Kay Goddard

Theses and Dissertations

ODS alloys, or oxide dispersion strengthened alloys, are made from elemental or pre-alloyed metal powders mechanically alloyed with oxide powders in a high-energy attributor mill, and then consolidated by either hot isostatic pressing or hot extrusion causing the production of nanometer scale oxide and carbide particles within the alloy matrix; crystalline properties such as creep strength, ductility, corrosion resistance, tensile strength, swelling resistance, and resistance to embrittlement are all observed to be improved by the presence of nanoparticles in the matrix. The presented research uses various methods to observe and characterize the microstructural and microchemical properties of two experimental ODS …

Fabrication And Characterization Of Surrogate Fuel Particles Using The Spark Erosion Method, Kathryn Elizabeth Metzger

Theses and Dissertations

In light of the disaster at the Fukushima Daiichi Nuclear Plant, the Department of Energy's Advanced Fuels Program has shifted its interest from enhanced performance fuels to enhanced accident tolerance fuels. Dispersion fuels possess higher thermal conductivities than traditional light water reactor fuel and as a result, offer improved safety margins. The benefits of a dispersion fuel are due to the presence of the secondary non-fissile phase (matrix), which serves as a barrier to fission products and improves the overall thermal performance of the fuel. However, the presence of a matrix material reduces the fuel volume, which lowers the fissile …

Pellet Cladding Mechanical Interactions Of Ceramic Claddings Fuels Under Light Water Reactor Conditions, Bo-Shiuan Li

Theses and Dissertations

Ceramic materials such as silicon carbide (SiC) are promising candidate materials for nuclear fuel cladding and are of interest as part of a potential accident tolerant fuel design due to its high temperature strength, dimensional stability under irradiation, corrosion resistance, and lower neutron absorption cross-section. It also offers drastically lower hydrogen generation in loss of coolant accidents such as that experienced at Fukushima. With the implementation of SiC material properties to the fuel performance code, FRAPCON, performances of the SiC-clad fuel are compared with the conventional Zircaloy-clad fuel. Due to negligible creep and high stiffness, SiC-clad fuel allows gap closure …

Novel Production Techniques Of Radioisotopes Using Electron Accelerators, Daniel Robert Lowe

UNLV Theses, Dissertations, Professional Papers, and Capstones

Non-traditional radioisotope production techniques using a compact, high power linear electron accelerator have been demonstrated and characterized for the production of 18F, 47Sc, 147Pm, and 99mTc from a variety of target candidates. These isotopes are used extensively in the medical field as diagnostic and therapy radioisotopes, as well as the space industry as RTG's. Primary focus was placed on 99mTc as it constitutes approximately 80% of all diagnostic procedures in the medical community that use radioactive tracers. It was also the prime focus due to recent events at the Chalk River nuclear reactor, which caused global shortages of this isotope …

The Challenges And Implications For Energy Education, Patrick A. Tebbe

Mechanical and Civil Engineering Department Publications

In March 2011, the Fukushima Daiichi Nuclear Power Station in Japan was hit by twin natural disasters of a 9.0 earthquake and a tsunami more than 10 meters high. The combination forced a shut down of the reactor and severed externally provided power. Backup generators and batteries, which at first functioned normally, were swamped and disabled by the tsunami waters. The subsequent loss of reactor core cooling led to rising temperatures that ultimately resulted in a partial melting of the fuel rods and several hydrogen explosions (produced by a steam-zirconium reaction). Eventually, the situation was brought under control, but not …

The Leading Contributor Of The Fukushima Daiichi Nuclear Power Plant Accident, Christopher Torres

Liberal Arts and Engineering Studies

No abstract provided.

Cellular Automaton For Simulation Of Oxide Layer Growth Influenced By Chromium Concentration Of Structure Material, Kuan-Che Lan, Yitung Chen, Ge-Ping Yu, Tzu-Chen Hung

College of Engineering: Graduate Celebration Programs

Chromium, an important alloying element, has been added in ferrous and nickel based alloy such as stainless steels and Inconel alloy to improve the corrosion resistance. High corrosion resistance of structural materials in extremely high working temperature is one crucial R&D objective of Gen IV nuclear power plants which propose to raise the thermal efficiency via high working temperature. A cellular automaton (CA) model based on the stochastic approach was proposed to simulate the process of oxidation and corrosion of structural material in flowing fluid. The relation of chromium concentration against oxide layer thickness during a specific period was found. …

Theoretical Study Of The Effects Of Di-Muonic Molecules On Muon-Catalyzed Fusion, Eugene V. Sheely

Theses and Dissertations

This document presents a theoretical study di-muonic hydrogen and helium molecules that have the potential of enhancing the muon-catalyzed fusion reaction rate. In order to study these di-muonic molecules a method of non-adiabatic quantum mechanics referred to as a General Particle Orbital (GPO) method was developed. Three mechanisms that have the possibility of enhancing the muon-catalyzed fusion rate were discovered. Two involve the formation of di-muonic hydrogen molecules, and the other uses di-muonic molecules to liberate muons stuck to ³He nuclei. The effects of muon spin on dimuonic hydrogen molecules was studied. The nuclear separation in di-muonic hydrogen molecules …

A Programmable Liquid Collimator For Both Coded Aperture Adaptive Imaging And Multiplexed Compton Scatter Tomography, Jack G. M. Fitzgerald

Theses and Dissertations

A novel, fully reconfigurable collimator device for gamma-ray and X-ray imaging was built and tested as a coded aperture. The device consisted of 10x10, 5x5x5 mm³ chambers. Each chamber either was filled with an attenuating liquid, stopping photons, or evacuated of the attenuating liquid, allowing the photons to pass through. As the pattern of on and off chambers was manipulated, different, semi-independent views of the gamma-ray source were found. Noise in reconstructed images decreased in all tests. Image reconstruction was performed with correlation methods and Maximum Likelihood Expectation Maximization (ML-EM). Using 10 mask patterns, the signal-to-noise ratio (SNR) in …

Managing The Future Energy Policy For Ireland: Examining The Role Of Nuclear Power, Declan Lynch, Angela Wright

Dept. of Organisation & Professional Development Publications

This study assesses the attitudes and opinions of Irish people towards the use of nuclear power, and specifically examines the concept that Ireland should use nuclear power to generate electricity in the future. Currently, Ireland has a prohibition on nuclear power, with little debate or discussion on same, and with scant amounts of information published on the subject as it relates to Ireland. Conversely, from an international perspective, there is a significant volume of literature available covering all aspects of nuclear power, generated from over 50 years of nuclear power operations. Nuclear power technology is perceived as being a relatively …

Evolutionary Optimization Of Electronic Circuitry Cooling Using Nanofluid, Manu Mital

Mechanical and Nuclear Engineering Publications

Liquid cooling electronics using microchannels integrated in the chips is an attractive alternative to bulky aluminum heat sinks. Cooling can be further enhanced using nanofluids. The goals of this study are to evaluate heat transfer in a nanofluid heat sink with developing laminar flow forced convection, taking into account the pumping power penalty. The proposed model uses semi-empirical correlations to calculate effective nanofluid thermophysical properties, which are then incorporated into heat transfer and friction factor correlations in literature for single-phase flows. The model predicts the thermal resistance and pumping power as a function of four design variables that include the …

Optimizing Fiber Cross-Sectional Shape For Improving Stability Of Air–Water Interface Over Superhydrophobic Fibrous Coatings, B. Emami, Hooman Vahedi Tafreshi

Mechanical and Nuclear Engineering Publications

In this letter, a mathematical force-balance formulation is developed that can be used to predict the critical pressure, the hydrostaticpressure above which the surface starts to depart from the non-wetting state, for superhydrophobicsurfaces comprised of highly aligned fibers (e.g., biased AC-electrospun coatings) with arbitrary cross-sectional shapes. We have also developed a methodology for optimizing the fiber cross-sections to maximize the critical pressure of the surface, using the Euler–Lagrange equation. A case study is presented to better demonstrate the application of our method.

Effect Of Fiber Orientation On Shape And Stability Of Air-Water Interface On Submerged Superhydrophobic Electrospun Thin Coatings, B. Emami, H. Vahedi Tafreshi, M. Gad-El-Hak, G. C. Tepper

Mechanical and Nuclear Engineering Publications

To better understand the role of fiber orientation on the stability of superhydrophobicelectrospun coatings under hydrostaticpressures, an integro-differential equation is developed from the balance of forces across the air–water interface between the fibers. This equation is solved numerically for a series of superhydrophobicelectrospun coatings comprised of random and orthogonal fiber orientations to obtain the exact 3D shape of the air–water interface as a function of hydrostaticpressure. More important, this information is used to predict the pressure at which the coatings start to transition from the Cassie state to the Wenzel state, i.e., the so-called critical transition pressure. Our results indicate …

Predicting Shape And Stability Of Air–Water Interface On Superhydrophobic Surfaces Comprised Of Pores With Arbitrary Shapes And Depths, B. Emami, Dr. Hooman Vahedi Tafreshi, M. Gad-El-Hak, Gary C. Tepper

Mechanical and Nuclear Engineering Publications

An integro-differential equation for the three dimensional shape of air–water interface on superhydrophobicsurfaces comprised of pores with arbitrary shapes and depths is developed and used to predict the static critical pressure under which such surfaces depart from the non-wetting state. Our equation balances the capillary forces with the pressure of the air entrapped in the pores and that of the water over the interface. Stability of shallow and deep circular, elliptical, and polygonal pores is compared with one another and a general conclusion is drawn for designing pore shapes for superhydrophobicsurfaces with maximum stability.

Optical Microresonator Based On Hollow Sphere With Porous Wall For Chemical Sensing, Hanzheng Wang, Lei Yuan, Cheol Woon Kim, Qun Han, Tao Wei, Xinwei Lan, Hai Xiao

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

A porous-wall hollow glass microsphere (PW-HGM) was investigated as an optical resonator for chemical vapor sensing. a single mode optical fiber taper was used to interrogate the micro resonator. Adsorption of chemical molecules into the nanosized pores induced a refractive index change of the thin wall and thus a shift in its resonance spectrum. the PW-HGM resonator had shown higher vapor detection sensitivity in comparison with a solid microsphere under similar test conditions. © 2011 Optical Society of America.

Hot Channel Determination And Burnup Analysis Of Missouri University Of Science And Technology Research Nuclear Reactor, Kelly Christopher Rogers O'Bryant

Masters Theses

"A burnup analysis has been performed on the Missouri University of Science and Technology (Missouri S&T) Research Nuclear Reactor (MSTR). With use of the Monte Carlo neutronics depletion code MCNPX, burned material was input into a neutronics model (burned model) in order better simulate MSTR core characteristics. Simulated burnup values of ²³⁵U for the past twenty years of MSTR operations totaled 14.266 grams, slightly less than the 14.527 grams reported by the reactor staff. A distribution of ²³⁵U was simulated and a burnup map was developed.

Using the updated fuel material, the hot channel of the current configuration of the …

Determination Of Linear Attenuation Coefficients Of Chemically Bonded Phosphate Ceramics, Jason Joseph Pleitt

Masters Theses

"Chemically Bonded Phosphate Ceramics (CBPCs) is a composite based material formed in a manner similar to cements. CBPCs have shown to be a good structural material with excellent thermal resistance properties. They have also been shown to have potential as a radiation shield. By incorporating various powders into the ceramic the improvement in its radiation shielding properties are examined. The method for obtaining the linear attenuation coefficients for CBPCs as well as MCNP simulated results for gamma and neutrons are presented"--Abstract, page iv.

Verification Of A Monte Carlo Model Of The Missouri S&T Reactor, Brad Paul Richardson

Masters Theses

The purpose of this research is to ensure that an MCNP model of the Missouri S&T reactor produces accurate results so that it may be used to predict the effects of some desired upgrades to the reactor. The desired upgrades are an increase in licensed power from 200 kW to 400kW, and the installation of a secondary cooling system to prevent heating of the pool. This was performed by comparing simulations performed using the model with experiments performed using the reactor. The experiments performed were, the approach to criticality method of predicting the critical control rod height, measurement of the …

Wavelet Based Contrast Limited Histogram Equalization For Contrast Enhancement Of Digital Mammography, Ashish Vighnahar Avachat

Masters Theses

"Mammography has been the most efficient tool for screening of microcalcification and cancer tissues; however, the raw images produced by mammography systems are usually of poor contrast. In order to use these raw images for early diagnosis; their contrast, sharpness and noise need to be enhanced. Among these important enhancement parameters contrast enhancement is critical. A novel algorithm is introduced which blends wavelet transforms with Contrast Limited Adaptive Histogram Equalization (CLAHE) for contrast enhancement. In this algorithm, the input image is decomposed to its low frequency and high frequency components in wavelet domain. Decomposed coefficients from different bands are then …

Quantification Of Stochastic Uncertainty Propagation For Monte Carlo Depletion Methods In Reactor Analysis, Quentin Thomas Newell

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Monte Carlo method provides powerful geometric modeling capabilities for large problem domains in 3-D; therefore, the Monte Carlo method is becoming popular for 3-D fuel depletion analyses to compute quantities of interest in spent nuclear fuel including isotopic compositions. The Monte Carlo approach has not been fully embraced due to unresolved issues concerning the effect of Monte Carlo uncertainties on the predicted results.

Use of the Monte Carlo method to solve the neutron transport equation introduces stochastic uncertainty in the computed fluxes. These fluxes are used to collapse cross sections, estimate power distributions, and deplete the fuel within depletion …